


Fascination

by angel1876



Series: Science With Gaster [1]
Category: Undertale (Video Game)
Genre: Deaf Character, F/M, Hand & Finger Kink, Hurt/Comfort, Medical Kink, Oral Sex, Porn with Feelings, Reader has a vagina but isn't referred to as either gender, Reader-Insert, Science Kink, Tentacles, Weird Sex
Language: English
Status: Completed
Published: 2015-11-25
Updated: 2015-12-17
Packaged: 2018-05-03 08:02:13
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 3
Words: 13,957
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5283074
Author URL: https://archiveofourown.org/users/angel1876/pseuds/angel1876
Summary: <blockquote class="userstuff">
              <p>You've fallen into the underground, and your time there hasn't been quite so pleasant. What's worse, you've found yourself in the care of Doctor Gaster, whom you're convinced is ready to experiment on you.</p><p>Turns out, the scientist is much kinder than you expected, and there are quite a few...interesting perks to letting him study you.</p>
            </blockquote>





	1. When You Met Him

You sat, curled up in the empty white room, exhausted beyond belief but unable to find the courage within yourself to sleep. Things had just gone from bad to worse. First you fall down a hole into a place filled with monsters, then you're attacked several times over, until finally you find yourself captured and locked away.

Everything hurt. Your clothes were torn, there were open wounds on your back and arms where the monsters had scratched you. Your fingers were cramped from clawing at the door in desperation. Every muscle in your body throbbed and ached from constant running for your life, and in the end, it was all for nothing. The beasts that caught you had mentioned experiments. You were there for human experimentation. All kinds of terrible images flashed through your mind, each worse than the last, and all you could do was sit in the corner and wait. You were sure you were going to die.

It felt like forever before the door opened, although you were sure it had only been an hour at most. You were on your feet in an instant, back to the corner, ready to fight with what little energy you had left. The monster that entered the room looked like a stereotypical scientist, if you ignored the skeletal appearance. He wore a clean white lab coat, and held in his hands a pen and a clipboard. For a brief moment, your eyes flickered to the door, planning on making a run for it before he locked it behind him. You weren't going anywhere.

"Hello there." he said. His voice was deep, but his tone was gentle. It would have been soothing in any other situation. He started forward, "My name is-"

"S-stay away!" you interrupt, pushing yourself harder into the wall. You tried to sound as hostile as possible, but it was hard when you could barely stand. "Don't...don't come any closer."

He paused there, and though as a skeleton his expression was fixed in a smile, the tiny orange and blue lights looking out from his sockets dimmed, like low burning candles. They also widened, the glow casting soft shadows over the rest of his face. He stood his ground, but held up a hand, palm out.

"You can relax. You're safe here. There's nothing to worry about."

You shook your head, hair falling in front of your face at the motion, though you didn't care enough to brush it out of the way. For a long moment, the two of you just stared at each other. He lowered his hand and instead wrapped his arms around the clipboard, hugging it to himself.

"They didn't tell me you were injured. Are you alright?" he asked. Then, with a sharper edge to his words, "Did my staff do this to you?"

You shook your head again. The cuts were from other monsters. Although you were pretty sure your shoulder was going to be bruised as hell later from being tossed onto the hard floor. Assuming you lived that long.

"Good." There was an awkward pause. He turned away from you and went to the door, opening it to call to someone on the other side. When he turned toward you again, his clipboard was gone, and he held a white box. He approached with slow, careful steps. "Look, it's only a first aid kit. See? I'll clean and dress your wounds for you."

He opened the box and showed you what was inside. Cloth, a bottle of clear fluid, cotton balls. He waited for a response, and when you didn't move, came closer still.

"Please..." You murmured, holding yourself tighter, wishing you could phase through the wall. He put the kit on the floor, and dabbed some of the fluid on one of the cotton balls.

"I'm not going to hurt you, I promise." He held out a thin, bony hand, "May I? "

You whimpered and cringed away, waiting for him to reach for you by force. But he didn't. He stood there, hand extended, waiting for you with an air of endless patience. You swallow, and against your better judgement, reach your own shaky hand out. His fingers were hard but they gripped yours softly enough it was hard to notice. He drew your hand toward him, extending your arm so as to give him access to the claw marks there. You flinch when the cotton ball made contact, expecting it to burn much more than it actually did.

The cuts weren't really all that deep, but they were covered in dirt and who knew what else, not to mention the dried blood that clung to your skin. It took him quite a while to clean it all away, but if it bothered him in the slightest it didn't show. When he was done, he pulled out a set of bandages and started to wrap the cloth around your arm.

"...what are you going to do to me?" You gathered up the courage to ask.

"Hmm?" His eyes flickered up to look at you. "I'm sorry, could you repeat that?"

"Um...w-what are you going to do to me?"

"For now, just this." he said, attention returning to the bandage. When he was done with that arm, he went to the other on, carefully cleaning the wounds on that one, too. "I'd love to examine you in detail, though, when you're feeling better. I've never had access to a human before. There's so much I'd like to learn from you. Maybe perform a few experiments here and there. Harmless ones, of course. Do you have other injuries?"

He looked at you again, expectant of an answer. "There's some on my back, too."

Back to your arm. "I'll get those taken care of as well. Then you can go lay down and rest, if you want. I'll have one of my assistants bring some food and water, and maybe a fresh change of clothes, too."

When he was done there, he grabbed another roll of bandages and wrapped your arm, then asked you to face the wall. A breath of pain hissed through your teeth as he peeled the remains of your shirt away to revile the gashes. They'd really done a number on you, and you could only imagine what it looked like. He let out a small, unhappy hum, and set to cleaning the wounds without a word.

"Are you going to have to use stitches?" you asked, hoping that they weren't deep enough to warrant them. He didn't answer. You pressed with a quiet, "Doctor?" but still he remained silent.

You took that to mean yes, you were going to need stitches. Your eyes close, and you stand there, waiting for him to use a needle an thread. Did monsters have painkillers that worked on humans?

It didn't come to that. He didn't sew them shut, he only covered them and said, "There we go. All done. How do you feel?"

You turn back around, but you keep your head down as you start to answer. "It's... much better n-"

His touch on the sides of your face cut you off. The tips of his fingers curled around the edges of your jaw as he coaxed your head upwards. "Look at me when you talk, please."

You met his gaze with wide eyes, and noticed for the first time that his own were focused on your mouth. Lip reading, you realized. He couldn't hear you. "Ah, um. Right. It's much better now, thank you."

"Good." He lingered against you for a few seconds more before pulling away, the place his hands had been suddenly rather cold in their absence. He folded them neatly in front of him and stepped back, "Shall we go to your room now?"

You nodded, and he put a hand on your shoulder, tugging you along behind him toward the door.

The rest of the facility was much like the empty room. White, twisting corridors littered with closed off rooms, the distinct smell of chemicals coming from several as they passed. The place was crawling with other monsters, many of them with teeth and claws like those who hurt you before. They watched you as you passed, and you recoiled, pressing into the scientist with a whimper.

"It's okay...you're okay." He cooed, his arm going around you, avoiding your bandages while still holding you closer. Very few approached. In fact, it seemed a good deal they were avoiding the two of you, walking wide circles around you like they were afraid. Those that did try to interact were waved off with a curt but polite, "I can't talk right now, please wait until later."

After what felt like an endless sea of hallways went by he stopped and opened a door into what looked like a small, but very nice guest room. There was a bed, a dresser, a lamp, and a bookcase on one end. There was a bathroom off to the side.

"Unfortunately, for your sake as well as that of the staff, you're going to be locked in here. If you need anything, knock on the door, the guard will be instructed to either provide for you, or come get me directly."

You bite the inside of your cheek, glancing away before remembering you had to look at him, "But...what if the guard...?"

"The guard won't hurt you. If he so much as lays a finger on you he'll have me to answer to."

"...alright."

He placed a hand on the top of your head, resting it there for a moment, mismatched eyes twinkling in a pleasant manner, "Don't worry. I'll make sure you're happy here."

He turned to leave, but before he could make it out of the room, you grabbed the sleeve of his lab coat. "W-wait. What's your name?"

"Dr. Wingdings Gaster. But Gaster is fine."

"Gaster...thank you, Gaster."

He nodded, "You're welcome, human. Have a good night."

And with that, you were left alone.

The following days passed by in a blur. You interacted with the guard only when you had to, ignored him when he entered your room to drop off the clothes you were promised and every meal left behind afterward. He made no effort to talk to you, either, slipping in and out like a ghost.

Every day, Gaster came by to change your bandages and ask you how you were doing. He was always nice to be around, focused on making sure you were comfortable and asking if there was anything you wanted before he left. Every now and then, you caught him talking in sign with the guard, only to shift to speaking out loud when he saw you.

"You're healing quite nicely." he commented a full week later while looking at your back. You had to agree with him, although you were somewhat disappointed when you realized several of the deeper ones were going to scar. You touch one on your arm, the texture rough under your fingertips. At least they'd closed up enough that you didn't have to keep them covered anymore.

He pulled your shirt down and waited for you to turn and face him before speaking again. "So, now that you've had some time to recuperate, I was wondering if perhaps you'd allow me to examine you?"

You hesitated. Of course, you knew this had to be coming sooner or later. That was why you were there, wasn't it?

"I assure you, it'll be quite painless." He pressed, and while his tone remained light and professional, you could see his pupils shrink and glow bright. As patient as he was, you could tell he was eager to get some research done.

You worry at your lower lip with your teeth, and finally, you nod. "Sure. Yeah."

It was the least you could do to pay him back for taking care of you, you supposed. Still, you couldn't say you weren't nervous. Friendly or no, you were worried.

The moment you agreed, he lit up, and before you knew it, your hands were held lightly in his. His fingers gave a small squeeze as he beamed at you, and despite yourself, a smile tugged at your lips at his enthusiasm.

With no further delay, tugged you out the door and down the hall.

The fact that the room he led you to was almost exactly like a doctors office didn't help. There were various monitors on the wall, tools on a nearby shelf, and of course, an examination table in the far corner. Gaster asked you to take a seat while he pulled out a clip board from one of the drawers. He wrote something down, probably the date, then he pulled out a small vial.

You sit on the table, the padding soft under you, not quite as nice as your bed but not uncomfortable. You're tense, recognizing a needle when you see one.

"We should get the scariest part out of the way first." he explained, holding out a hand for yours, again waiting for you to accept or decline.

You reach for him, flinching when he draws your arm out, the metal point glinting in the light. "How many of those are you going to take?" you asked.

"Just the one, for now. To find out what your blood's made of. It's easier if you don't look."

You shake your head, "I...can't just not look."

"You can squeeze my arm if it helps."

That you did. Your grip was a little too tight as he delicately brushed his fingers over the crook of your elbow. He put a little pressure on either side of the vein before sliding the needle in. There was a sharp twinge, but it wasn't as bad as you were imagining. You watched blood flow into the vial in spurts, keeping time with your heart.

It took less than a moment for it to fill up, and he slid the needle out, replacing it quickly with a band aid. "Thank you," he said as he rubbed at it to soothe away the lingering prickle. "You've no idea how much I appreciate this."

He set the sample on the counter and returned to your side, clip board in hand.

"Now, I'm going to need an extra set of hands for this. Don't be alarmed." He waited for you to agree. The moment you did, the glow in his eyes changed color, shifting to green. A set of transparent hands the same shade appeared, hovering in the air in front of you. You gasp, startled despite his warning.

"H-how do you do that?"

"Magic." The hands floated a little closer, "May I touch you?"

"Yeah." He cupped your face, fingers brushing over your jaw, moving steadily upward. As the apparitions worked, their real counterparts scribbled away at the paper. When he looked back up at you, you asked, "How many of those can you make?"

"As many as I need. Although I can only concentrate on so many at a time. Oh, what's this?" His fingers focused on your cheeks, "I've never seen the muscles here structured this way. These are usually positioned much further back. Can you open your mouth for me?"

You did, and he leaned in close, a soft, excited noise escaping him. "Your teeth! Are those molars?"

Two fingers slipped inside to touch the teeth near the back of your mouth. He traced over them, not just the molars but also the canines. "I always thought humans were predators, but this changes your digestive capabilities completely. You're omnivores. Hmm." He dipped his fingers under your tongue to press against the soft flesh there, "These appear to be your saliva glands. Judging by the fact that you're not eating right now, they're constantly active. And they produce quite a lot, too."

Just as he said, the more he prodded around, the more liquid gathered. You couldn't swallow with how wide your mouth was, and he showed no sign of losing interest. He took a moment to explore the roof of your mouth, commenting on the soft spot just beyond your hard pallet, and then he pulled your tongue out as far as it could go, gently pinching it between two fingers. Saliva started to drain over your lip.

"I wonder how sensitive your taste buds are...ah, wait a moment, let me just..." A second set of glowing hands appeared on the other side of the room, only to vanish in one of the cupboards. They reappeared a moment later with a plastic cup, which was then held under your chin. "Spit in here, please."

When your mouth was empty, he wiped away the drool that had gathered with one set of hands, while the other put a cover on the cup and set it next to the blood sample.

He wrote a few more notes down, silent save for the sound of pen on paper. The translucent fingers still lingered around your face, tugging your chin up, only for the second pair to reach for your neck. You let out a small gasp at having such a vulnerable area toyed with, but nothing in his touch felt threatening. He looked absolutely enthralled as he rested his hands there, feeling your pulse and the air moving in and out of your throat.

Slowly, he brushed lower, to the curves where your neck met your shoulders. He curled his fingers inward, pushing against the muscles underneath, massaging you. A small shudder went down your back, gripping at the tables padding.

"You're doing well. Very well." he said, lowering the clipboard a bit to look down at you. He was so much taller, unintentionally towering over you. You felt what must have been a third pair of hands curl around the bottom of your shirt, "Now, I'd like to take this off."

As each time before, he waited for you to agree before moving on. Your shirt was neatly folded and placed on the counter. Without a bra provided, this left you bare under his gaze. Despite knowing this was purely for scientific knowledge, you felt heat creep up into your face. You swallow hard and look away, stomach clenching as he paused to write.

Each pair of hands shifted position. One settled to rest near the waist, the other squeezed your arms in an effort to reassure, and the third wrapped around your breasts. He lightly dug his fingers in like he'd done with your shoulders, feeling the glands beneath the skin. He rubbed methodical circles from the outside inward, pinching and tugging your nipples when he reached the center.

As he touched you, you felt that warmth spread, gather in your stomach, your breath catching every time he hit a particularly sensitive area.

"This is where your mammary glands are located, right? I thought so, most mammals have them. Since you have two breasts, would it be safe to assume you'd only be nursing one to two offspring at a time?"

"Mostly, yeah." You said, flushing worse when his gaze turned upward so he could see your answer. "It's possible to have more than two kids at once, though."

"Are you alright?" He stopped, eyes dimming as they focused on your face. By then, you knew that was his version of a frown. He reached up to cup your cheeks again, "You're warmer than before. Is it a fever? Human...you need to tell me if you're feeling unwell. I can help."

"No, really, I'm fine." You felt mortified. This shouldn't be any different than a trip to the doctor, and here you were getting all worked up. You didn't even know him that well. Sure, he'd been nice, but it'd only been a week. Worse still, there was a very strong part of you that didn't want him to stop.

"If you're sick-"

"I'm not sick."

"...then what does it mean?"

The worry in his expression convinced you to tell the truth. You knew he had to see your mouth to understand you, but you couldn't look at him when you answered. You kept your gaze focused down at his chest. "It means...I liked...what you were doing..."

Once it was out, you glanced up despite your nerves. He looked bewildered. "You liked what I was...?" He said slowly, then comprehension dawned, "Oh...I see."

"I'm sorry."

"No, no, nothing to be sorry about. Do you want to stop? If it's...triggering such responses... I don't want to make you uncomfortable."

"It's okay."

"Listen, the samples you've already given me are more than I could have dreamed for. So if you're just saying that because I'm housing you, then there's no need. You don't owe me anything."

"It's fine, really, you can keep..." You paused, realizing that maybe he was the one who didn't like where this was going. "Unless you don't want to keep going?"

"I do." His voice lowered, closer to a loud whisper, "I...want to see everything...and...I'd very much like to study these responses. If you'll let me. Again, you don't owe me anything. And even if you did, sexual encounters aren't a form of payment."

"Ah-" You flush harder at how direct he was. "Um...I know, but...I..."

"Do you...want this, as well?" He sounded hesitant, but also eager, and you could see the green flames start to perk up again. You could see his interest burning, and knew that he was only holding back for your sake.

"Yes, I-I think I do."

With no further hesitation, the hands went from your cheeks to your shoulders, pushing you into your back. He ran a pair down your sides, and the third started tugging your pants down. Like your shirt, he took a moment to fold them up and put them safely to the side.

You were hyper aware of his gaze as he lingered over every inch of you, looking away only to jot a few more quick notes out. His hands drifted lower, and lower, and you clenched the soft padding you lay on.

He ran fingers through your hair and gripped your hips as he coaxed your legs apart, your warm folds already damp. You gasped as he pulled at the edges of your slit, intent on the soft, waiting flesh there. He ran a finger over you, from a point down near your entrance up near your clit. He brought that same hand up toward his face and examined your fluids, even bringing it close to breathe in your scent.

"Lubricant." He mused for a few seconds, before the hand lowered to trace the path again. A slow, easy up and down pattern, occasionally stopping to rub over your entrance. "Assuming this entire area is sensitive, you'd need to produce a lot of it to make penetration comfortable. There is...a lot of excess skin here. Does it feel good?"

You nod, chest heaving. 'Good' was an understatement. It wasn't like you'd never pleasured yourself before, but this was different. This time it was someone else's fingers trailing over you, and the difference left you breathless.

"What parts are most sensitive, though? That's the question. Where should I touch you, human?"

You reach down and direct him upwards, to your clit. He leaned forward, taking in the little bundle of nerves with another pause to write on his clipboard. He ghosted a thumb over it, and you let out a moan, teeth clenched at the rush of heat between your legs. "P-please...ah..."

"Fascinating..." He said, rolling your clit between his fingers, watching you clench. Two fingers slid into your wet hole, to feel the spasms directly. "You are so, so fascinating."

With a glance toward your face to gauge your reaction, he curled his fingers inside you, and as he did so he hit the sweet spot right there near the front. Every muscle inside you shuddered and tightened, a much lower groan pulled from your throat. Gently, he brushed your hair off your face, his thumb trailing over your mouth. Without thinking, you part your lips and run your tongue over it. He slips his thumb into your mouth without a word, running it along the inside of your cheek before touching your teeth.

His fingers curled inside you once more, firmer, actively seeking out the spot that was making your head spin. You can feel yourself tighten and flex around the apparition, as if your body was trying to pull it in deeper. His hand was covered in your fluids at that point, and you could hear your flesh squishing as he moved.

The noise struck a chord in you, and you felt that pressure building up faster than ever before. Your moans jumped in pitch, becoming a squeal just as you slipped over the edge. Your mind went blank, your back arched, giving tiny, quiet whimpers as you jerked and shuddered in waves. Somewhere, you realized you were biting down on the thumb in your mouth, and let go, not knowing if it hurt or not since it wasn't actually part of him.

You went limp as the last tremors flooded through you, your eyes glazed as they stared upward at the ceiling. Two of the three sets of hands disappeared. The fingers inside of you slipped out and, as the other hand held a fresh cup, collected as much of your fluids as it could. You whined a little, overstimulated, but he was careful enough it didn't bother you too much.

A few final notes were taken down as you were handed your clothes, the floating extremities helping you get dressed before they vanished as well. The moment you were fully clothed, the doctor put his real, physical arms around you and pulled you into a hug.

"Thank you. I know I've said it before, but thank you, so much." he said, and when he pulled away, you could see the blue and orange lights of his eyes, glowing the brightest you've ever seen them.

You blush again and glanced away, a smile of your own forming as if his was contagious. "No problem..."

"Come, let's get you back to your room. I want to get started on these samples as soon as possible."

"Of course."

His arm stayed around you as he led you back to your room, although this time you're more focused on the weight of his hold than on the monsters watching you as they walk by. The scientist thanked you again with another hug, before bidding you goodnight and rushing back to the office.

About a half hour after he left, you knocked on the door, and asked the guard if there was any way he could teach you sign language.

**Notes for the Chapter:**

> Hey there! Please let me know what you think~ ^^  
> One down, two chapters to go.


	2. When You Loved Him

Several months passed since your arrival to the underground, and though it was hard for you to believe, you found yourself quite comfortable living in the lab. You were no longer confined to your room, although there were several places that remained off limits to you, and you did have a curfew you had to abide by. The same monsters that had once terrified you no longer seemed as scary, and they in turn felt the same toward you. You'd even managed to make a few friends along the way, including the guard, although he only stood by your room at night by then.

Despite your new-found freedom, you spent quite a bit of your time reading, since most everyone was busy with their work. When you weren't doing that, you were practicing your sign language. You were by no means skilled, but you knew enough for basic conversation. The only one who knew you were learning it was the guard, whom you'd sworn to secrecy.

Gaster still came every day to see you, sometimes just to chat for a few minutes before taking his leave. Sometimes, he invited you to share a meal with him. It was always nice, the two of you sitting at a lone table, talking about whatever came to mind. He usually used this time to tell you about his experiments, while you reminisced on your old life back on the surface.

His interest in your body still burned strong, even with regular examinations every few days. It was amazing how quickly you'd grown used to his constant prodding, not worried in the slightest when he slipped a needle in, or scrapped the side of your arm for skin samples. His eyes lit up every time he hovered over you on the medical table, always with a new question to ask or an absent observation.

You couldn't help but smile at the way he went on whenever he found something new.

Of course, eventually, he'd run out of things to find. He had no one to compare you with, no way to pick out patterns either physical or behavioral. You knew enough about the scientific method to understand that he could only find out so much about humanity from a single specimen. You brought this up to him during an examination as he trailed his transparent hands up and down your back. He'd gotten distracted by your tailbone, and after explaining what it was, you caught him before he could fall into another series of note taking.

"Hey, Gaster?"

"Hmm?"

"What are you going to do once you've learned everything about me?"

He lowered the clip board and hugged it to his chest, "I'm going to fill out a proper report and file it away for later use. Make a few copies as well, just in case something happens to the original."

"What are you going to do with me?" You rephrased the question.

"If you're afraid I'm going to make you leave once my research is complete, don't be. I have no intention of letting the monsters out there get another chance at you."

"So...I'm just going to stay here, then?"

"It's the safest option for you. If you leave the lab, you could be spotted by the royal guard." His eyes dimmed a bit, "Are you becoming uncomfortable here? I know it might be a bit claustrophobic, not being able to leave. If there's anything in my power I can do to help, you know I will."

"No, no, I'm fine, I just..." You trail off. It was embarrassing to admit that you were worried he might loose interest in you. Your look down, away from him, "I'm fine."

He put the clipboard down and reached for your face, gently wraping his fingers around your jaw as he coaxed your head back up. You wince inwardly when you saw the orange and blue flames, knowing he'd banished the extra sets of hands. He looked at you, voice lowering as he asked, "Are you really okay?"

You swallow, cheeks warming under his touch despite the serious situation. It was rare that he physically touched you when you weren't wearing anything. "Um..." you hesitate, then make the plunge. "Are we still going to be friends? After...all this?"

His expression softened, the tension easing as his eyes flickered bright. He bumped his forehead against yours, and you could feel the heat emanating from his sockets. "Of course we will. Why ever wouldn't we be?"

"I-I was... I mean..." You trail off a second time, a small whine entering your tone.

His hands drifted down, brushing over your neck, down to your shoulders, before he pulled you in for a hug. The fabric of his lab coat was soft, pleasant against your bare skin as you wrapped your arms around him. He leaned his chin on the top of your head, giving a small hum that made his collarbone vibrate against your cheek. "We'll still be friends, human. I admit your body draws quite a bit of my attention, but I enjoy spending time with you outside of work, too."

He held you as long as you wanted, his own grip firm until he felt yours start to go slack. He pulled away, taking a moment to brush back a few strands of hair, hands returning to their previous position cupped around your face. "Do you want to take a break?"

"Nah. You only have the legs left, right? Let's go ahead and get that done first."

He chuckled and touched the spot where his nose would have been to your own. "So long as you're up for it."

He withdrew and took up his clipboard again, ready to start writing. Green overtook his gaze once more, and he ran a pair of hands slowly over you leg. One started at the inner thigh, and the other at your hip, fingers massaging, easing down inch by inch. As he worked to map out the muscles resting under the skin, a second pair slid from the back of your neck up into your hair, curling inward to scratch at your scalp.

You close your eyes and leaned into him, relaxing as he moved over you knee, down your calf muscles, all the way to your ankle. He took a moment to rotate the joint a little, watching how it moved. He moved on to the other leg, mirroring what he'd done by starting at your ankle and making his way to your hip. Your breath caught as he felt his way up your thigh, that familiar blush heating your cheeks.

"Humans have to support a lot more weight than skeletons do." He mused, and you opened your eyes to find him looking at you. "Our legs only have to support the weight of our bones, while yours have to support flesh, muscle, organs. Your legs have to be strong. I think I'm going to work on a way to measure how strong you are, not just your legs but your arms, too."

You nod, grinning at him, "Sure. I don't mind."

He beamed back at you a moment, before taking a few more notes, hands reaching for your clothes to help you get dressed.

He didn't need to escort you to your room, but he did it anyway, a hand on your shoulder as you walked. You appreciated the gesture, and bid him a good day before you went inside.

Not three hours later, there was a knock on your door. You almost jumped out of your skin, not expecting company of any kind at that time of the day. Everyone was busy, and the guard wasn't on duty yet. When you opened the door, you found Gaster, hands folded politely behind his back, eyes bright but flickering, not something you'd seen them do before. You pause, taking them in a moment, before greeting him, "Oh, hey. What's up? Did you get the weight thing set up already?"

"No, not yet. It's going to take a couple days before I get that done. I want to make sure it's accurate to the nanogram. Actually, I came to see you. Can I come in?"

"Yeah, sure, come in."

You step aside to let him through the doorway, closing it behind him. He picked up the book you'd been reading, turning it over so he could glance at the back. He looked up from it to you. "It's been a while since I read this one. It was good. Don't worry, I won't give away the ending."

"That's okay, this is the second time I've read it. It's one of my favorites."

"How many of these books have you gone through?"

"About half of them I think? I just really liked that one."

He hummed a little, and put the book down, his hands returning to rest behind his back.

"So," he said, "I wanted to talk to you."

"Is everything alright?"

He nodded. "Yes. Don't worry, it isn't anything bad. Talk might not even be the best word for it. I want to show you something. You've shown me so much, and I wanted to return the favor."

"Okay...sure, what is it?"

"Well." He moved his hands from behind his back to clasp in front of him. The shadows over his skull danced in time with the flames. Was he...nervous? "As you know, humans differ quite a bit from monsters, but I'm not sure you realize exactly how much. The one thing we share in common is the soul. The soul is our essence, who we are, humans and monsters alike. The difference, though, is that monster souls are basically their entire body." He spread his arms out to the sides. "This, what you see before you, is my soul. This is me. Now, you..."

He took a step closer, a hand raised, reaching out to hover a few inches over your chest. His eyes stayed trained on you face as he continued. "Think of your body as a housing area. A shell of sorts, made of flesh and blood. Your soul rests within this covering. Right here." He closed the distance, bony fingers placed over the center of your chest.

"...is that what you want to show me?" You felt a shiver run up your back. He was staring so intently at you his gaze almost felt like a physical thing.

"Yes." He pulled his hand away, "But only if you...if..." He cleared his throat. "I'll understand if you're not interested. By no means should you feel obligated to agree."

"This is kind of a big deal, isn't it?" You ask after a few moments.

"It is. It's the very culmination of your being, pulled free of the shell it resides in. Not permanently, of course. I'll put it back. Assuming you trust me to take it out in the first place. I want you to feel safe. I wouldn't do anything to hurt you."

"...I know you wouldn't." You said, and you saw him fidgeting with the sleeve of his coat. "Shouldn't we be doing this in the examination room, though? So you can take notes?"

"I don't need to take notes. I know what a human soul looks like." He held up a hand before you could say anything. "Please don't ask me how. It...wasn't under the best of circumstances, I don't like to think about it."

At that, his eyes darkened, an edge entering his tone, and you could guess what might have happened. You felt your fingers brush one of the scars on your arm before you even realized you'd moved your hand. The last human to fall into the underground wasn't as lucky as you were, it seemed.

He followed the motion and you stopped, but it was too late. He'd seen you. The scientist softened with a sigh and reached for your wrist, tugging your arm out to expose the claw marks that trailed from elbow to hand. His fingers were feather light as they trailed up and down the damaged tissue. "I'm sorry about all that. We weren't always so spiteful of humans. At one point, our two species were close to becoming ally's. Then the war broke out, and a lot of us forgot that not every human has to be our enemy."

"It's...it's okay..." You didn't know what to say to that. What could you say to that? You'd read their history book, you knew what your kind had done. "H-humans were the ones who started the war though. So I can understand why some of you would be upset with us."

He shook his head. "No one started the war. It was an accident. A misunderstanding that both sides were unwilling to resolve until it was too late for diplomacy."

Gaster fell silent, still tracing the scars, soothing over a wound that had healed as much as it could. You raised your free hand to touch his own, and he curled his fingers around it instead, absently rubbing into your palm with his thumb.

"Hey..." He didn't notice your mouth moving. You leaned in closer, putting your face close to his, "Gaster?"

His flinched, and his eyes brightened, shrieking into little pin pricks. He moved away, folding his arms behind his back. "I'm alright. As I said, I really don't like thinking about the past. My apologies."

"You don't have to apologize. We can talk about something else. Um...did you... did you still wanna do the thing?"

The little flames flickered, and he coughed, glancing to the side and back again. "Do you want to?"

You nodded.

He motioned you over to the bed, saying, "I'd prefer to sit down for this."

You sat on the edge of the bed, and he took a seat next to you, the two of you turned toward the other. With all the care of someone touching glass, he placed both hands against your chest, your heart beating under his fingertips. He pulled away slowly, and you felt part of yourself go with him. A soft tugging at your core as he eased something out of you.

Your soul glowed a light blue, reminding you of frost on a cold winter morning. You gasped, watching it float there, just above his hands. For several seconds, you were frozen, gripping your chest as if you could fill in the void where your soul went if you pressed hard enough. You'd understood the concept he'd explained, that he wanted to pull your essence out of your body, but only once he'd done it did the full gravity of the act click into place.

"Wow..." You whispered the word.

"Yes. It's rather different, isn't it? Is it okay?"

"Yeah. It's...fine."

With effort, you lowered your hand, using it to clutch at the sheets instead. It didn't hurt in the slightest, but the sense of displacement was jarring to say the least. Gaster waited another few moments, letting you recover, or maybe giving you a chance to call it off. When you didn't say anything more, he started talking.

"The human soul is quite the powerful thing. We're not entirely sure why, but I believe it might have something to do with the fact that it's so much smaller than a monster soul is. Because of it's size, humans would have had to develop ways of protecting themselves in order to survive. Hence the covering of flesh. The structure of the human soul varies from monsters too in the fact that it can produce a substance that will keep it living on after the body perishes. Both these things suggest defensive evolution from a once weak ancestor. The ancestors of monsters, on the other hand, were much bigger, and never needed it. They remained the same as humans developed into the stronger creature they are today."

"Why don't any of the books talk about this?"

"The existence of the soul isn't information open to the public at this time, on orders of the king."

"Why not?" That seemed to be some really important information Asgore was keeping from his people, especially considering humans were their enemy.

Gaster shrugged. "I never asked. I'm sure he has his own reasons. He isn't the type of king to issue laws without purpose."

You were about to ask if it was at all possible to be because of what happened to the kings son, but you stopped yourself. You didn't want to tread on another subject that might bring up bad memories.

He continued. "That's why it means so much that, when you found yourself down here, you didn't hurt anyone. I know you didn't. There wasn't a speck of dust on you when we first met. Your soul is stronger than that of any monster, but despite the fact they attacked you, you didn't lash out in return. Even under threat of death, you didn't strike back. I don't care what the monsters outside this lab might think, that act alone deserves recognition. Thank you, human."

"Y-you're welcome?" You reply, half murmuring the words. It didn't feel like a thing he should be thanking you for. Thank you for not killing anyone? You frowned, hit by the realization of just how deep the divide between the two species truly was.

The scientist let out a small laugh, and with a careful, calculated motion, brushed the side of your soul with the very edge of his thumb. Chills shot through you at the contact, spider webbing down your arms and legs with a shudder that took away the air from your lungs. The squeal died into silence, and for several dizzying moments you forgot to breathe.

"G-Gaster? What-what was...? What was that?"

"I touched you directly. Was it too much?"

"No. No, it-it wasn't. It..." You took in a deep breath, "Ca...can you do it...again...?"

At that, the flickering died down, his eyes back to giving off a strong and consistent glow. He beamed at you, and you could have sworn you heard a thread of relief in his voice. "Yes, of course I can."

He touched the edge of your soul with the tip of a finger, and eased it from the upper curve of the heart downward. You gasped, teeth clenching as you doubled over. Just that simple movement sent a wave of tingles through every nerve in your body. Gaster took his time, his touch slow and lingering, resting under the rounded point at the bottom before pulling away to let you recover.

You fell back on the bed, unfocused gaze fixed on the ceiling. "...wow..."

"Was that good?" He asked, and you nodded numbly. "Here, let me try something."

He brushed against the other side, with two fingers this time. You went ridged, a low moan straining at the back of your throat, and you could feel him tracing a pattern into your soul. Simple spiral shapes, inching down from the top toward the bottom. By the time he pulled away, you were a shivering mess, hardly able to catch your breath.

"G-Gaster...!"

"You're warm." He cooed, glancing from you to your soul and back again. "And smooth, like the surface of a marble. I can feel your energy, human."

"Ah..."

"It's lovely." He concluded, letting out a low hum. "You feel wonderful."

Once more, he moved his hands closer, both of them. You tried to brace yourself for it, but the sensation of his palms cupping around you was overwhelming. Your head went back, knees bending so your legs pressed into the side of the bed, you gripped the sheets so hard your fingers started to hurt. The skeleton wasn't even moving, his hands still, just holding you. What little air you had left released itself in a brief cry, leaving your head spinning when you couldn't bring yourself to inhale.

You went limp when he let go, tiny shock waves still sparking through you even after he'd stopped.

"I think that should be enough for now," he said, and you knew it was because if he kept going you were going to pass out on him. He leaned in over you, bringing your soul to your chest to push it back in. You shuddered as it went, the void it had left behind filled as if it had never gone.

Before he could move away, you sluggishly grabbed at his wrists to hold them in place. You could feel the shape of his bones under the cloth of the sleeve.

"Human?" He questioned, not fighting your grip on him. You took a moment. You took several. Then you wrapped your arms around him, pulling him down onto you. He responded in kind, hugging you to himself, face nestled in your hair. He shifted so the two of you were laying side by side, keeping his weight off of you.

"That...was amazing..." you said. "I...n-never thought...that was incredible..."

"I'm glad. I was hoping you'd enjoy it." He nuzzled into the top of your head, a hand going up to brush through your hair. He massaged the area just below the base of your skull, and you sighed at his touch, pressing closer to him.

As soon as your breath returned to it's normal, steady rhythm, you pulled away enough that you could reach for the top button of his lab coat. You looked up into his eyes, taking in the bright, mismatched flames. "May I?" you asked.

He paused, first from confusion, then from hesitation. "You...you know you don't have to. I was only-"

"I know I don't have to." You smiled, scooting up so you could lean your forehead against his. You didn't stay like that for long, he couldn't see your mouth with your faces that close. You leaned back and went on, "I want to. May I?"

Gaster nodded.

You rolled the both of you over, so you were the one hovering over him, and went back to the button. It was undone with single smooth motion, as was the one below it, one by one, all the way down until you could open it up and reveal the light grey shirt beneath. He shrugged the coat off, letting it pool behind his back, murmuring a quiet, "If you're sure..."

His eyes were flickering again, and you gave him another smile as you pulled his shirt up. Under the cloth, he was exactly what his hands and head suggested: A skeleton. You paused at the sight of his spine and rib-cage, considering how to go about this. Your fingers brushed along the sternum, with a glance toward his face to gauge his reaction. He met your gaze shyly, his gaze a soft, fluttering green. Just as you registered what that meant, a pair of hands came to rest on your shoulders, kneading at them.

"Please, keep going. That feels nice." He said.

Encouraged, you applied a little more pressure, rubbing up and down the bone. With your other hand, you ran a path along the side of his rib-cage. Under your touch, he shivered. Experimentally, you slid your fingers between a set of ribs, taking hold of one and rubbing from one side to the other. That got you a moan, and another shudder that made his joints rattle.

Abandoning the sternum, you focused you attention on the ribs, first just touching them with your hand, then lowering you head to press your mouth against them. You felt a hand, his actual, physical hand, entangle in your hair as the ghostly extremities continued to massage your shoulders.

You wrapped your mouth around the bone and sucked on it, the taste of calcium and earth on your tongue. As you worked on his ribs, you also touched his spine, trailing from as far up under the rib-cage as you could get down toward his pelvic bone. With each vertebra you counted off, the noises he made deepened. He doubled over, fingers curling tight enough in your hair that it started to hurt. The instant he noticed what he was doing, he pulled away to grab at the sheets instead.

"Ah. H-human, that feels so good..."

You grinned into his bone, teeth clicking against it. Opening your mouth, you softly bit down, pulling another moan from him.

As you reached the pelvis, the noises he made became more strained. Tiny whimpers escaped as you touched him through his pants, his hips rocking into your hand. His voice was low, almost too quiet to hear. "P-please. Ahh. Please..."

You pulled away from his ribs and scooted downward until your knees found the floor. Settled between his legs, you pulled his pants down as far as they'd go without you having to move. The sides of the bone were slightly grainy, but not at all unpleasant to touch. Like with his ribs, you pressed your mouth to him and ran your tongue over his surface. He rolled against you, emitting a sharp whine.

It wasn't long before the extra set of hands twisted into the back of your shirt, clinging to it as the real ones still griped the bed covers. You licked, and sucked over him, keeping a steady rhythm while he panted and quivered.

When he came, it was quiet. A whimpering, desperate cry followed by complete silence as he went stiff under you, spasming in short, quick waves. You gentled your tongue when he started, but kept going, trying to draw it out as long as possible for him.

He went limp, save for a few faint twitches from the aftershock. You crawled back up on the bed, wrapping yourself around him, nuzzling your face into his chest plate. "Careful, human." He nudged you away and rolled you back over onto your side. "Don't want your skin to catch on anything sharp. Especially that close to your eyes."

"I won't scratch myself."

He gave your shoulder a squeeze. "Even so, I'd rather not risk it."

With that, he sat up, and pulled his shirt and coat back on, though he left it unbuttoned for the time being. Once he was covered, he laid down, pulling you back into a hug. He held you tight, a hand bushing along your hairline at the base of your skull, and hummed into your ear. Although you knew he couldn't hear it, you hummed in return, nestling yourself in closer.

The two of you stayed like that in silence for over an hour, until he had to leave and check on his other experiments. He offered to share dinner with you once he was done with his work, and grinning, you agreed.

Before he closed the door, he leaned in and pressed his teeth to your forehead, fingers ginger at your lower jaw. "I look forward to seeing you later, human."

"And I, you, Gaster."

A full week went by, days blurred together as you spent more time with the scientist both inside and outside the examination room. One day, you woke up early, and went out to the kitchen to get some breakfast. There was a heavy feeling in the air, all of the monsters going quiet when you walked by. Some of them stared at you. Most of them couldn't seem to look at you at all.

"Um...hey, excuse me, is there something on my face?" You tried to joke, but the atmosphere was more than a little unnerving. The most you got was a small shake of the head as they hurried away from you.

You bit your lip after the third monster fled, wondering if perhaps you'd done something wrong. Suddenly, you didn't feel like getting anything to eat. On your way back to your room, one of your friends approached. A rather bulky lizard creature, with wide, nervous eyes that, like everyone else, couldn't seem to meet your gaze. She pulled you aside, hands rubbing together, murmuring a few things under her breath that you weren't sure were directed at you or if she was just talking to herself.

"Alphys?" You said. "Is everything okay?"

"Um...no. N-no, it's not. I-I'm sorry."

A trickle of foreboding went down your back. "What's wrong? Everyone's been acting weird today. Did...did something happen?"

"Y-yeah. Um. There. There was a-um. An a-accident. With...with our head scientist. With, um. D-Dr. Gaster."

"Wait, what happened? Is he okay?"

She shook her head. "He...a-appears to have been...v-vaporized. It...was j-just an a-accident, t-the core..."

You feel your heart clench, that moment of denial hitting you hard. He'd just been there, with you, the day before. He couldn't just be gone. He couldn't.

"No.." You breathe, and she winced.

"T-this isn't...about him, h-human. You...you need to leave. He, he was the o-one who was...he didn't want to...r-report you. The...the others have been...t-talking...it isn't..."

"I can't leave!" Your voice cracked, a hand going to clutch at your chest. "T-the monsters out there, I-I barely survived last time."

"I-I know! But...but s-someone's going to...to report you! There's t-too many of them...o-one of them's going to g-go to Undyne, a-and if...if she finds you h-here...you won't have a chance! You h-have to go! I'm s-sorry, but it...it isn't safe, human! Please...believe me..."

You could see tears gathering in her eyes as she grabbed for your shoulders, meeting your gaze.

"Y-you... you need to r-run, human."

**Notes for the Chapter:**

> One more chapter to go~
> 
> Fun fact: Gaster was lying about the knowledge of souls not being open to the public. He removed all the books available to the Reader and lied because he didn't want the reader to learn about what was needed to break down the barrier.
> 
> What better excuse than 'Because the king said so.'
> 
> He just didn't want the Reader to be afraid nor feel guilty for not losing their soul to the cause.


	3. When He Found You

You ran.

The caverns flooded by in a blur as your feet scrabbled over uneven terrain, the rocky ground threatening to trip you at any given turn. If you fell, you were dead. You were probably dead anyway. Behind you, the sound of metal clanging followed, relentless and determined. A spear made of blue light cut through the wall nearby, the resulting shower of rocks pelting you as you passed.

You had no idea where you were going, had never been in this part of the underground before. The corridors twisted and turned, not a single path available to you, but several. They came together and formed a dark maze that would have been pitch black if not for the faint, twinkling lights on the ceiling. You couldn't see the end of any given hall, couldn't tell if your efforts would leave you trapped at a dead end. If you could just shake off the monster at your back, you were sure you could hide away until she gave up, but the sound of your footsteps kept her well aware of your location.

She'd catch you if you tried slowing down to quiet the noise you were making. All you could do was keep going and hope she took a wrong turn somewhere.

Another spear hit the ground near your feet, far too close for comfort, and your heart leapt in your chest. You took a left, followed by a right, then another left, choosing your route at random. You couldn't have her picking out a pattern to follow if she lost track of you. Just as you went to go left again, though, something pushed you.

You didn't see what it was in the dark, nor did you have time to stop and look. It pushed you hard enough that it almost knocked you over. Without enough time to correct yourself, you were forced into stumbling to the right. Pebbles exploded just behind you, a shower of them hitting the ground in your wake.

At the next intersection, you had a choice of either turning or continuing in the same direction. You veered right, only to be pushed again, this time away from the turn. Whatever it was pressed into the small of your back for several seconds, urging you forward. Around the next corner, you came upon a stretch of tall grass. If you weren't being chased, you wouldn't have gone in. Grass? Growing underground? For all you knew, you could be stepping unaware onto someone's back.

She threw another spear, and this one was close enough to graze you. The light was sharper than any human blade, and cut easily through your skin. You hissed in a breath, feeling your blood start to drip down from the wound. One would think that a weapon made of energy would be hot, that it would burn the wound shut even as it made it, but no. It was closer to ice than fire, still biting into the skin even after the harsh edge that caused it had dissolved.

The plants were soft, smooth and flowing around you like hair. You didn't make it far before the unseen force again found you, this time not pushing, but grabbing. It locked around your ankles and held firm, another pressure finding your shoulders and somewhat cushioning the impact when you hit the ground.

You shrieked, sure you'd been led into a trap, and there was a new pressure over your mouth, muffling the sound. It wasn't until then you realized what it felt like. Hands. Disembodied hands, familiar in concept, but wrong. They were shivering, clammy things that clutched at you, dragged you into the cave wall. In panic, you squealed again, fighting against their hold. One of them curled around your throat, squeezing hard enough to cut off your air and silence you.

Something ran by. You heard it, the sound of footfalls and then the clack of rock against rock, a stone flung into the shadows down at the end of the cavern.

The monster ran right past you, and as she went the hands appeared all over you, tight and restrictive. They dug into your arms and legs and shoved you into the ground, the one at your throat increasing pressure to the point your head spun. The sound of metal on metal faded, and you were released. You gasped, curling in on yourself, as if you could stop that from happening again if you just lay still.

A hand nudged your shoulder. When you didn't move, it grabbed your shirt and tugged. You whimpered, closing your eyes, shying away from the thing.

This monster had powers like Gaster. Given that almost everyone in this place wanted you dead, the idea of a being that could summon restraints at will was terrifying. The hands' touch vanished, but you knew you weren't yet alone.

You stayed where you were, listening hard for the guard and hearing nothing. As your breathing slowed to a more even rhythm, you realized what the unseen monster had done. Your pursuer was gone. It had helped you.

"...hello?" you called out, voice quiet, not wanting to draw unnecessary attention back to you.

In response, the hand reached for your shoulder, again tugging at your sleeve. You felt another appear underneath you, pushing upward, the motion firm, urgent. As you dragged yourself to your feet, they helped you up, wrapped around your upper arms, holding on almost painfully tight. Now that you didn't have to run, you squinted, looking down at them, trying to see them despite the low light.

There was nothing there. You squinted harder, lifted an arm up to get as much light from the twinkling stones above you, but there really was nothing. They were invisible. Although...you could see the one at your left outlined in the blood that was dripping from the wound just above it. You movements agitated the cut, drawing out more blood which then pooled over the hand. As if in response, the pressure increased, and you winced, teeth clenching as you grabbed at it.

They both let go, shifting instead to your back, and they pushed again. Not nearly as hard as before, but still insistent. You hesitated, and another pair appeared to tug at your wrists. Should you trust it? It did save you, but at the same time, the way it was trying to drag you off somewhere without showing itself first made you hesitate.

It turned one of your hands over, a fingertip tapping at the center of your palm. Then it began to trace. Slow, careful letters, giving you a chance to put them together in your head. A single word.

_S-A-F-E_

It waited for you to repeat the word, before pulling at you again. You glanced uneasily back toward the opposite end of the hall, where the fish monster had gone. She'd be back, and you couldn't be there when she did. You didn't know where else you could go, either. Any other monster would either report you or attack you themselves, and you weren't sure how much more running you could take before you collapsed.

This was the first monster that had offered help since you left the lab. You supposed at that point, your only option was to trust it and hope for the best.

It led you back through the maze of corridors, where the light was much brighter, sharp against the eye. You kept a close watch on your surroundings, jumping at even the smallest of sounds, but there was nothing, no sign of life at all. It wasn't a long walk, not really, but it felt like one. Your legs and back ached, your head pounded, your shoulders protested the weight pressed against them.

The hands brought you to a door. It was large, and looked out of place against the wall. It wasn't carved into the rock, nor was it wooden, as with most doors and buildings you'd seen. It was smooth, shiny and clean, pure white like marble. As you approached, the hands gave a final nudge toward it, then vanished, leaving you to look up at the thing.

You took a breath, bracing yourself for whatever might lay inside, and you opened the door.

It was a room, white and smooth like the door. There was a single light on the ceiling, enough to illuminate every corner at once. It was empty. Nothing at all inside but space, and now, you. The moment you stepped in, the door behind you closed. Instantly, you turned and tried to open it, but it wouldn't budge. It was locked.

"Ah, no, n-no let me out!" You pulled at the handle, breath catching in your throat. Trapped, you were trapped, it trapped you. What was it going to do now? No, no. You peeled your hand away from the handle and folded your arms across your chest. It was trying to help you, right? Why would it get you away from the guard just to kill you itself? There'd be no point.

Was it in there, with you? You couldn't see its hands, maybe...?

You swallowed, and turned, back against the door, facing the room.

"Hello?" you called out, timidly inching forward. You went slow, not wanting to run into whoever it was. The air around you shifted, and a shiver went up your back. You were being watched. "Is...anyone there?"

Something soft, cold, and very, very wet touched your hand. You turned, scrambling back and away from the...thing, that had appeared behind you. You didn't know what to call it. Was it a monster? You'd never seen any monster like this one. They were all different, but this one, this one was just _wrong._

A tentacle, dripping with a black, syrupy substance recoiled back into what looked like a large puddle on the floor. As you watched, the puddle struggled to take shape, elongating into something that was much taller than you. Your back hit the corner, and there you stayed, shuddering as you felt your hand start to tingle. You looked down to see the dark liquid that had been left on your hand fade away, like it was never there.

It shrieked, a garbled mess of sound, half growl and half wail. The pillar of ooze seemed to falter under its own weight, bowing to one side. Two smaller limbs extended from the main body, near the top, the ends meeting the ground keep it from falling. With effort, it pulled itself up again, the dripping, arm like appendages bending in what appeared to be an attempt to mimic the curve of the elbow. A pair of trembling hands white as the marble walls around you extended at the ends of the limbs. They were solid, cracked in places, like clay that had been left out in the sun. At the center of each hand, there was a large, circular hole. When the creature flexed its fingers, the joints popped, grinding against each other with every movement.

At the top, another solid, marble form came out of the mass. It looked almost like a skull, but like the hands, it was malformed. No teeth, just a gaping, melted mouth that stretched upward into a smile. There was a large crack that went from one corner of the mouth up into the eye. The other eye, too, was cracked, this one bigger, enough that it stretched from the top of the socket around to the back of the head.

Two small grey flames looked at you from within the broken sockets. For several moments, it made no further move.

"H-hi there..." you murmured, frozen in you little corner, feeling smaller than ever at how big this thing was. It practically loomed over you, even as it stood on the opposite end of the room.

It raised a hand to its head, and waved it out to the side. You recognized the motion, the creature had responded in sign. It continued, hands moving slowly.

_"Hello human are you okay?"_

It paused, then it came closer. The ooze that its body was made of allowed it to move in the same way a snail did, although the dark trail it left behind evaporated quickly enough. The moment you flinched, it stopped in its tracks. It fidgeted, fingers twisting around each other with a nervous flutter. Then it pulled them apart to sign again.

_"You're hurt let me help please I won't hurt you."_

It didn't wait for an answer before it started for you again, the urgent air about the creature clashing with its sluggish pace. When it finally reached you, it took hold of your wrist, the other reaching for the cut by your shoulder. You could feel it shake, could see its pinprick eyes spark and burn. It dripped onto your arm, over the cut, the liquid cool against your skin. It didn't dissolve, instead, it reshaped itself, wrapping about the wound to form a living bandage.

The creature asked again,  _"Are you okay?"_

You nodded, switching to sign yourself.  _"I'm fine."_

_"Are you sure?"_

You nodded a second time. The worry you felt radiating from the monster put your fears that it meant you harm at ease.  _"Yes I'm sure. It's not that bad. Thank you for helping me. Who are you?"_

It stiffened, and then reached for you, slow, as with every other movement. Its bony, cracked hands were cool against your skin as it cupped your face, fingers curling under your jaw, its head dipping down to touch your foreheads together. Its eyes met yours, burning low as it held your gaze. You felt your heart flutter in your chest, recognizing the gesture and the expression.

"Gaster?" You whispered out loud once he pulled away.

 _"Yes. It's me."_ He did a quick motion where he formed a G with his hand and touched it to the side of his head, waving it out like the sign for hello.  _"Gaster."_

You mimicked the gesture.  _"Gaster. What happened? They said you were gone."_

_"I am. I fell."_

_"But you're here."_

_"No. Not here. I fell. I'm still falling. This is a projection. I'm trapped in the core."_

_"We need get you out. Tell me how. I'll-"_

He cut you off by raising a hand to pull your attention back to him.  _"You can't. No one can. My partner tried for years and he failed."_

_"What do you mean for years? You fell three days ago."_

_"I can see him. I can see everyone. I'm everywhere but I'm nowhere. I'm outside time."_  His form faltered. The flow of goop increased, and as it drained down, his upper body started to sag into his lower body. His hands twitched as he went on.  _"I can see all the things that could happen. Countless possibilities but not once has he ever managed to fix the machine he needs to free me."_

 _"If I can't get you out how do I help you?"_  The shift in him was alarming, his already unstable figure appearing to melt before you. He was smaller, closer to your height. The lights in his eyes were gone, leaving the sockets dark and empty.

_"You can't. It's okay. I'm not here but I'm not going anywhere. Won't leave you alone again. I'm sorry. I didn't mean to."_

_"It's not your fault. There's really nothing I can do?"_

_"You can stay safe. Stay here. I'm sorry. I know it's too small. I'm sorry."_

He looked like he was going to fall completely apart, and you couldn't hold yourself back. You closed the short distance between the two of you and pulled him into a hug. The cool, thick liquid that made up his body poured down your arms, a sharp, static whine coming from the scientist at the contact. The next thing you knew, he was wrapped around you, the dark ooze enveloping almost every inch available. It seeped into your clothes, pressed into every limb. The only part of your body he left untouched was your face, so you could breathe.

His hands dug into the back of your shirt, solid and hard among the sea of liquid. You tightened your grip around him, felt the ooze give to your touch, until your arms found your chest. Another garbled, incoherent burst of squeaks and growls came from him as he clung to you.

You didn't stop trying to hug him. He flowed through your fingers, too soft to grab onto even as he cradled you within himself. It was a protective embrace, almost to the point of desperation. For a long time, he just held you.

There was a wet squelch when he finally did pull away, quite a bit of him staying with you as he eased back. Thick ropes of fluid connected you to him, and you shivered despite yourself. It wasn't long before that tingling sensation started up again, the dark substance evaporating off of you little by little.

Gaster seemed to have collected himself, standing tall once more as he signed,  _"I'm sorry. I missed you."_

_"I don't mind. I missed you too."_

The lights in his eyes were back, wide and dim in their sockets. _"I know. The last few days were awful. You shouldn't have had to go through that. Everyone chased you."_

 _"Yeah. But I'm okay now."_  After the way he'd hugged you, you felt like he needed that reassurance.

 _"..."_  He started to sign something, but then he stopped mid motion. For a moment, you thought you saw the flow of goop increase, but he caught himself before he started melting again.  _"Yes. You're safe. I'll make sure you stay that way."_

You started to ask him what was wrong, and just like him, you stopped before you could get the first word out.

It clicked. You stared at him, the blood draining out of your face, stomach twisted into a knot. Didn't he say he could see everything that could happen? You wouldn't even pretend you could wrap your mind around that idea, but...if he saw everything that could happen, didn't that stand to reason he'd seen the less fortunate outcomes of all those close calls you'd had? You thought of the shallow cut on your arm, and knew what would have happened had that spear been a few inches more to the right.

Your hands hovered in the air, fingers curling inward before you pulled them to your chest. What could you possibly say to that?

The lights in his eyes flickered, and you winced, knowing your hesitation gave away your guess.

 _"I will keep you safe."_  he repeated.

_"But what about you?"_

_"Don't worry about me. I'm not going anywhere. Please. Nothing can change what has been done. I'd rather we not focus on it."_

It took you a moment, but you nodded.

_"Thank you. You are a kind human."_

"Thank you." You murmured back out loud, glancing away. Yet again, it didn't feel like something he should be thanking you for.

He brought your gaze back to him with a wave.  _"I know you learned sign for me. You've done well. I saw how much you practiced."_

The flames brightened, if only a little, and you offered a small, strained smile in return. _"I'm glad I did. Though it was supposed to be a surprise."_

_"How were you going to go about it?"_

_"When I first started I planned on telling you how much I appreciated what you did for me. When we started spending time together I thought it'd be better to tell you what a great friend you were instead. Then I thought about something else. I wasn't sure if I was going to do it or not. Never did make my mind up. I could have done it a month ago if I had."_  You took a breath.  _"I want to tell you now even if it isn't a surprise anymore. I love you."_

Maybe right then wasn't the best of times to be confessing, but you wanted him to be sure he knew. While you knew him well enough to be confident in his word, you'd thought him dead for three days. Even if he wasn't going anywhere, you wanted to say it, just in case.

A low, rumbling gurgle left him, and you could have sworn it was a chuckle. _"We never did get around to saying it did we?"_

Your smile came a little easier. _"We didn't. It's silly isn't it? All that time together and neither of us said a word."_

 _"Let me make up for that. To say I love you would be an understatement at best. What I feel for you is immeasurable in words. My affection has grown past simple interest in your human form. I adore you as a person. I adore everything you are have been or will be. I always will."_  He paused to let his words sink in.  _"It's as if you have a positive charge and I have a negative charge."_

You couldn't stop the snort of laughter that came out, a hand reaching impulsively to cover your mouth, though you lowered it a moment later so he could see you speak. "Did you just...?"

He beamed at you.  _"I feel an attraction between us."_

_"You know. Even if there were no gravity on Earth I think I'd still fall for you."_

_"Are you amylase? Because you make everything sweet."_

_"If you were a triangle you'd be acute."_

He gurgled again, his form almost tipping over from the force of his laugh.  _"Cute?"_

 _"Yes. You're cute."_  You took a step closer.  _"So cute I want to try hugging you again."_

 _"Are you sure?"_  His eyes dimmed at that.  _"Like this?"_

_"Why wouldn't I?"_

_"I dripped all over you."_

_"What if I like you dripping all over me?"_  You reached out to brush over his chest. Like before, your hand sunk into him, his liquid body clinging to you when you pulled away.  _"It's different I admit. But it's still you. I love you."_

He fidgeted, fingers twitching in the air before replying.  _"I love you too."_

A tendril of ooze eased out of his side, the thing wrapping around your wrist to tug you into him. Once more, you found yourself enveloped in his cool, wet form. His face nestled into the top of your head, quiet static coming from somewhere within him. He soaked your clothes and touched your skin through them.

Try as you might, you still couldn't return his hold, couldn't get a grip on him. There just wasn't anything solid to grab onto.

Then again...maybe you were reaching for the wrong thing?

You pulled an arm free of him and found one of his hands, pulling it close so you could hug it to your chest. He intertwined his fingers with yours and gave a small squeeze. A grin formed, and you moved him up to your mouth instead. You nuzzled the back of his hand, smearing him over your face. He tasted of fog in the early morning, with a much thicker texture. The liquid evaporated in your mouth, his vapor going into your lungs when you breathed in and visible in the air when you breathed out.

The bones of his hand no longer tasted like calcium, but rather like dust. Cracked and flaking under your touch, it felt as fragile as it looked. You took great care as you left kisses over each knuckle. He shivered between your fingers, the black substance tightening, rolling over you. It pressed into your back and shoulders, squeezed your legs, rubbing at every aching muscle in your body. A moan parted your lips, your tongue slipping out a moment later to trace one of the cracks. You followed it inward, toward where the hole was at the center of his hand.

The static deepened into a hiss as you worked, his pressure moving around to your front. He kneaded your breasts, the ooze sucking gently at your nipples, more of it creeping up the back of your neck to flow through your hair.

When you reached the hole, you dipped your tongue inside and traced your way along its curve. The moment you touched it, he let out a whine, his other hand clawing at your back. Once you came full circle, you pressed your mouth to the edge, the surface of your teeth resting on bone.

Thick wetness gathered itself between your legs, inching upward to brush against your slit. He didn't need to undress you to seep into your folds, coating every inch. Despite not being able to hold him, he could most certainly hold you, curled about your limbs to support you when your knees buckled. He lowered you to the ground, letting you take a safer position on your hands and knees rather than risk touching you while you stood. You kept his hand in yours, lowered your head to touch your mouth to his fingers, coaxing two of them to extend so you could close your mouth around them.

You moaned, eyes closing as he teased pressure along your clit, cool and wet against heated, swollen flesh. He pooled into you, gathered some of himself into a fluid tentacle that filled you inside. It curled, expanded, rubbing over every inch you had to offer. He found the sensitive spot just inside of you and focused much of his attention there. A groan seeped from your throat to vibrate into his hand, your hips rocking reflexively into him.

The noises he made kept shifting, a gurgle here, a cackle there, unintelligible chirps and snarls that came out at random. His face burrowed into your hair, muffling the sound, but you could still hear it come out every time you ran your tongue between his fingers, or gave the digits a light suck.

He started up a simple rhythm, first moving against your inner walls then tugging at your clit. It was a slow process, leading you little by little toward the edge, leaving you clenching his hand and whimpering, whining at the warmth that throbbed within you. You whispered his name around his fingers, repeating it under your breath. "Gaster, please. Gaster, ah, Gaster. Oh, please...please..."

Your words dropped off into a frantic, uneven pant as you felt yourself hover just before climax, the soreness of your muscles forgotten as every one of them tensed up. It was agonizing in the best of ways, every joint locking into place as your insides burned for release. When it came, it came hard, spasms jerking at your stomach and hip muscles, making you curl into yourself as your lungs refused to let go of your last breath of air.

You twitched and shivered there on the floor, Gaster continuing to rub and tease until all at once you relaxed, slumping limp to your side. Your chest rose and fell in deep, even breaths under the dripping blanket that was the scientist. His hand softly pulled away from yours to rub along your temple, the other tracing little patterns up and down your arm, while the rest of him just hugged you tight.

The two of you stayed like that for a long time, his touch soothing you long after you started to doze off, held safe inside of him.

**Notes for the Chapter:**

> And here we are, chapter three. Looks like they had a happy ending after all. ^^
> 
> Hope you all enjoyed! I really had fun writing this. I fully plan on writing more Gaster/Reader stuff in the future, though I'm probably going to stick to oneshots, at least for now.
> 
> Thank you so much to everyone who reviewed and left me kudos~


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